Using the build envinronment, i built today MyPaint for window 32 to test those commits :
Andrew Chadwick committed 2dc0c42
symmetry: new axis derives from display centre
Andrew Chadwick committed 5556f45
symmetry: refactor, manage states via UI
As i had some sketches made with a previous build and MyPaint once loading them didn't had anymore the same center of symmetry as before i saved them.
I noticed that it seems to work, if i disable the Symmetry , move the canvas, then re-enable the Symmetry button, the center of the symmetry have changed, and seems to be overall at the center of the canvas (on my screen i mean) .
That is good, but then i found no way to set that center with -precision- so i could retrieve exactly the center of symmetry i needed for resuming work on my sketches.
After lots of fiddling with disabling symmetry/moving canvas/enabling symmetry, give a brush stroke to see where it is, i was able to roughly get it in required position
Still, it's a lot of tinkering before going there.
So maybe i'm missing the correct way to do it, is there any way to display where is the current center of the screen in MyPaint ?